This invention relates to a winding, method, and to a continuous drum type surface winder, adapted particularly for winding slit web material onto individual core segments carried on a common core shaft, and more particularly to a method and winder adapted to wind a slit web into individual rolls of substantial diameter, such as 60 inches or greater, on wide and relatively small diameter core shafts.
In the winding of large diameter shippable high quality rolls of web material, including films, non-woven materials, paper, paperboard material and composites onto cores, the slitting and winding operation is preferably positioned in 15 line with the web forming, and converting process. Such a continuous winding arrangement reduces production costs and scrap, and permits quick identification of process control problems. Continuous winding requires that the handoff of completed rolls, the transfer of the individual slit webs at high speed onto corresponding core segments, and the initiation of the winding process on the new core segments all be handled smoothly and at line speed.
The continuous winding of large diameter slit rolls on wide machines has presented significant problems. A particular problem arises from the fact that a long, small diameter core shaft bends under its own weight, and exhibits critical speed limitations during speed up and prior to web transfer. Such critical speed limitations are primarily the result of core shaft deflection resulting in harmonic and dynamic imbalances. Such critical speed conditions produce vibrations that interfere with the web transfer, and can result in an improper or defective start, and a start in which the rolls lack sufficient hardness. Also, shaft deflection can cause roll quality problems when winding slit rolls to a large diameter. The above identified problems are particularly acute when the core shafts are quite small such as for example, shafts for supporting three inch inside diameter cores across a wide width that may exceed 200 inches, and for winding to roll diameters that may exceed 60 inches.
A need exists for a continuous winder and method of operating a winder in which large diameter slit rolls are wound at wide machine widths in a continuous operation, in which core shaft deflection and critical speed conditions are controlled, and in which the building roll set is controlled for density throughout the winding process.
This invention provides a continuous surface type drum winder and method for winding slit webs onto individual core segments of wide web materials at high speeds into large diameter rolls on small diameter cores. In particular a winder and winding method provides the transfer of split webs of line speed onto cores supported on a long and slender core shaft, as previously described.
A first or primary driven drum is provided with a driven primary nip roll that is rotatably mounted on support arms. These arms are pivotally mounted on primary arms that rotate about or in common with the axis of the drum. The primary arms are further provided with a slot, recess or other means by which the ends of a core shaft are supported or guided in the initial stages of winding, such that the core shaft is sandwiched between the driven primary nip roll and the driven primary drum thereby eliminating core shaft resonances and deflections that cause critical speed limitations and wrinkling at the web transfer and startup.
The buildup of the roll segments, i.e, the individual rolls, on the core shaft is begun while the core shaft is supported by the primary arms. The geometry of the arms, the primary or main drum, and the nip roll is such that the core shaft is supported during the web transfer, and during the initial roll building, in the manner that assures that the core shaft and cores are straight or parallel with the surface of the primary drum, and a good start is obtained by way of proper loading by the primary nip roll.
Also, during the roll building phase, the primary arms are programmed to move from a roll change position to a toll transfer position, in which the core shaft and the rolls thereon are transferred to a pair of support arms referred to herein as secondary support arms. The secondary support arms arm associated with a support drum that is movable on the secondary arms and in relation to the secondary arms so as to cone into a supporting engagement with the building rolls while the rolls continue at all times to be engaged with the main winding drum. In addition, the primary nip roll also continues in engagement with the winding rolls, so that the winding of the rolls continues as if on a two drum winder in which both drums are driven, either in a speed or torque mode as desired, and nipped by a driven rider roll. The primary nip roll is released after the winding rolls"" weight supplies sufficient nip loading with the support drum.
The changing roll diameter is known at all times through a reading of angle transducers incorporated into the pivot arm for the primary nip roll and by the position of the secondary support drum on the secondary arms. The loading of the primary nip roll and the loading of the secondary support drum may be controlled by roll diameter as well as roll weight to provide roll density and deflection control.
The slow movement of the winding roll set, when carried by the primary arms to the position of hand off to the secondary or support arms, results in very little change in web length and therefore very little change in web tension, and allows the winding of the full roll set diameter while the roll set is maintained in part on the main drum to help minimize winding roll deflection.
The winding set, at the beginning of the wind following web transfer, is sandwiched between the main drum and the driven primary nip roll, and the core shaft is retained in slots defined in the primary arms. The secondary arms, after the completed roll set is unloaded, return to a start position that permits the primary arms, through a total rotation of about 60xc2x0, to deliver the partially wound core set to the secondary arms, while maintaining contact by the driven nip roll. The winding roll builds until initiating contact with the counter-balanced secondary support drum that is being driven at line speed. This condition of three roll or three point engagement is maintained throughout a major portion of the building of the rolls of the roll slot while the secondary arms and support drum cooperate with the primary drum to carry the weight of the building rolls and maintain the core shaft in a straight-line condition.
Upon the roll set achieving sufficient size that a rider roll is no longer required, the primary arms and their associated nip roll are fully retracted to permit the placement therein of a new core shaft with cores, the ends of which shaft are retained in a slot in the primary arms and supported on a fixed cam surface. A transfer shoe-tape web curing system is pivotally mounted on an axis common with axis of the main drum, and rotationally modes under the on-running web, and comes to rest at a point upstream of the nip and between the new cores on the core shaft and the building roll. The primary nip roll lowers onto the new core shaft. The nip roll drive goes into the speed mode to speed-up the new cores and core shaft. The primary arms then rotate approximately 5xc2x0 so the core shaft moves off the cam surface and into the arm slots where the cores come to line speed by running engagement with the web on the drum at a position just prior (upstream) of the point where the web is lifted off of the drum by the transfer shoe.
An adhesive spray applicator is mounted between the primary arms and has individual spray heads operational to spray the web surfaces with adhesive upstream of the core shaft. The primary arms then rotate another approximate 5xc2x0 which triggers the adhesive spray. At the same time a precision ground cut off knife comes out of the shoe into the split webs and impales the webs. The web tension and the momentum of the building rolls pull the webs through the knife thereby causing a clean straight line cut, with the adhesive causing transfer of the individual webs onto the new cores. At the same time, adhesive on the cut tails causes the tails to be attached to the surfaces of the respective completed rolls.
Then, the secondary arms index the fully wound set of rolls away from the primary drum and into a braking position where braking torque is regeneratively applied by the secondary drum to stop roll rotation. The wound roll set is then moved to an unloading position. At the same time, the shoe type web cutting system is pivoted by its arms to a lowered rest position, and the new core set, with the webs attached, continues to be wound, retained in the primary arms, and loaded against the primary drum by the driven primary arm nip roll. In this sandwiched position, the core shaft is maintained substantially free of deflection, providing a hard winding start of the individual split web sections on the respective cores, with the hardness being controlled by torque and pressure supplied by the primary nip roll. Natural deflection of the core shaft is eliminated or controlled that otherwise could cause wrinkling of the web at the start and which could cause critical speed problems.
The apparatus and method of this invention provide certain features and advantages believed to be unique to winders of this kind. These include elimination of or control of critical speed problems and related core shaft deflection problems common to continuous winding of wide and, or large slit rolls.
The sandwiching of the new cored shaft between a main driven winding drum and a driven nip roll at and following roll change eliminates the critical speed and natural deflection that causes wrinkling at the winding start.
The transfer shoe system with a pop-up knife ensures a straight clean transfer regardless of web speed.
The driven primary arm nip roll assures a good hard start and proper hardness profiling through a programmed nip and programmed torque control as a function of the winding roll""s diameter through a position sensor on the driven primary nip roll""s pivot.
A slow and controlled movement of the winding roll set from about xe2x88x9220xc2x0 from a vertical center line through the main drum to about +30xc2x0 winding position provides excellent roll support and causes very little web length change and therefore very little web tension change, and allows winding to the full roll set diameter while supported on the main or primary drum to help minimize deflection of the core shaft and the winding rolls.
The driven support drum supports the winding roll set in the winding position to also help minimize the winding roll""s deflection.
The driven support drum assures that the building rolls have proper density profile through the programming of the nip pressure and the torque control of the drive. This system approximates the well known two drum winding system used extensively in the industry for stop/start slitting and rewinding operation.
The driven support drum is also used to support and stop the wound set after transfer by providing regenerative braking.
The primary support arms with the nip roll provide safety and ensure that the winding roll set is contained inside and within the working surfaces of the two winding drums and prevent lateral movement of the winding roll set until the set is handed off to the secondary arms.
Shaft sensing devices are incorporated in the secondary support arm to prevent excessive loading of the core shaft from excessive loading of the support drum.
The secondary arms arc used for safety to insure the winding roll set is contained inside the two winding drums. They are also used to prevent lateral movement of the winding roll set and to eject the finished roll set.
A position sensing device is incorporated into a secondary arm pivot to counter balance the arm assembly through support arm cylinders to prevent excessive loading of the core shaft by the support arms that would cause shaft deflection.
It is accordingly an important object of the invention to provide a continuous two drum surface type winder and method, in which a core shaft is supported throughout the entire winding process, from web transfer, startup, and completion, in such a manner as to eliminate bending and deflection, and reducing critical speed problems.
A further object of the invention is the provision of a two drum type winder in which a lay on roll is operable to provide three point winding control throughout a major portion of the winding of a split web onto individual core segments on a core shaft.
A still further object of the invention is the provision of a winder as outlined above, in which a secondary winding drum is controlled on secondary arms. In such a manner as to support the weight of the building rolls on the core shaft so that the core shaft may remain relatively straight throughout the winding process.
Other objects and advantages of the invention will be apparent from foregoing and following descriptions, and the accompanying drawings claims.